Randomised controlled trialindependent cross-checkabstract only checked★ key study I-GRN-01 in-depth review
Is it gluten or another wheat component?
Fructan, Rather Than Gluten, Induces Symptoms in Patients With Self-Reported Non-Celiac Gluten Sensitivity.
Overview
Skodje GI et al.. Gastroenterology 2018 · PMID 29102613 · DOI 10.1053/j.gastro.2017.10.040
In people who think they react to gluten, a wheat sugar (fructan) caused more symptoms than gluten.
Does the study support the specific claim? Partly · Methodological quality: high
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Gluten vs fructan
- How was the study done?
Blinded crossover RCT
- How many people, animals or samples were studied?
59
- What was actually found?
Fructan, not gluten
- How large was the observed effect?
GSRS 38.6 vs 33.1
- What do the results mean in everyday life?
Symptoms may come from wheat carbohydrates
- What are the study's limitations?
Small
- What does it say about Elawady's specific claim?
Partly supports 'not gluten'; says nothing about coeliac disease
- Do the results apply to Germany and Europe?
High
- What can explicitly not be concluded from this study?
Coeliac disease
Scientific in-depth review
1. Full reference
- Authors
- Skodje GI et al.
- Journal
- Gastroenterology
- Year
- 2018
- Identifier
- PMID 29102613 DOI 10.1053/j.gastro.2017.10.040
- Verification
- verified – PubMed efetch 2026-10-25
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
None stated.
2. Research question
Do gluten or fructans cause symptoms in self-reported NCGS?
3. Study design and population
- Study design
- Randomised controlled trial – Randomised double-blind placebo-controlled crossover trial
- Population
59 adults on self-instituted gluten-free diet, coeliac excluded
- Country
Norway
- Period
Oct 2014-May 2016
- Sample size
59
- Inclusion and exclusion criteria
Coeliac disease excluded
4. Methods and endpoints
- Exposure / intervention
Gluten 5.7 g/day or fructans 2.1 g/day in muesli bars, 7 days each
- Comparator
Placebo
- Endpoints
GSRS-IBS score
- Statistical methods
Linear mixed model
5. Actual results
- Results
GSRS-IBS: gluten 33.1, fructan 38.6, placebo 34.3 (P=0.04); bloating 9.3, 11.6, 10.1 (P=0.004); fructan > gluten (P=0.049). No difference gluten vs placebo.
- Absolute risks
not applicable
- Authors' conclusion
Fructans, not gluten, induced symptoms in self-reported NCGS.
6. Strengths
- Blinded crossover
7. Weaknesses
- Small; short challenges
8. Risk of bias
- Orienting tool
- RoB 2
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- low
- Rationale
Simplified judgement.
9. Assessment of the statistical interpretation
Small absolute differences.
10. Relevance to the specific claim
Partly supports C-GRN-01 (gluten not the trigger in self-reported NCGS).
11. Independent contrary findings
12. Transferability to Germany and Europe
High (Norway).
13. Overall methodological judgement
Good trial; shows symptoms from wheat may be due to fructans.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | high |
| Risk of bias | low |
| Precision of results | moderate |
| Directness | direct |
| Reproducibility | partly replicated |
| Consistency with the overall evidence | mixed |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
15. Linked fact checks
- 'There is no such thing as gluten sensitivity'; the real problem is only that white flour turns into a glue-like substance. – Studies supporting the claim
- Gliadin (a wheat gluten protein) increases intestinal permeability via zonulin, which the archive presents (by listing the studies under the white-flour rule) as relevant to everyone eating white flour. – Studies contradicting or limiting the claim